Human skin protects the human body from the external environment. When the skin is wounded, the process of wound healing begins as blood fills the wound site and the reduction of granules of platelets as well as the activation of the Hageman factor is initiated. Blood coagulation is a provisional defensive mechanism, protecting the exposed damaged tissues and allowing migration of cells during wound healing.
The classic model of wound healing is divided into four phases: inflammatory, reepithelization phase, proliferative and maturational. In the inflammatory phase, immune cells migrate to the wound site from the blood vessels. Then, growth factors and signaling molecules that induce the formation of granulation tissue are released. In the absence of severe infection, the inflammatory phase is usually short.
In the proliferative phase, granulation tissues are formed at the wound site similar to reepithelization phase. The granulation tissue is composed of fibroblasts and inflammatory cells as well as extracellular matrix components including immature collagen, fibronectin, hyaluronic acid, etc. It is important in wound healing that the granulation tissues quickly fill the wound site and form an organized structure. In the reepithelization phase, a new epidermis is formed and the epithelial layer is restored as the open wound is covered by a layer of keratinocytes. The cells begin to migrate from the wound edge or from the remaining dermis to the living connective tissue under a scab floating through the wound site.
When the reepithelization is completed, the wound area is reduced through a series of processes involving increase and construction of the connective tissue. In the maturational phase, coagulated cells of recovery phase and capillaries are removed gradually. If the tissues are formed excessively or are not degraded normally, scar will remain.
The general wound healing process is explained above. In wound healing, it is also important to treat the wound without side effects or scars as much as to treat it quickly. Accordingly, well-balanced filling of the tissue cells through inhibition of inflammation and control of growth factor expression is important and efforts are made to find materials having such activities.
Also, various efforts are made to extract active ingredients for wound healing from a variety of medicinal materials. Accordingly, a method allowing for more effective extraction of the active ingredients is required.